Process for making a container for storing food

Abstract

A container for storing product and a process and apparatus for making the container. The container comrises a paperboard outer container and a plastic inner container which has been drawn and blow formed into the outer container. The container is characterized by plastic screw threads which extend from the plastic inner container around the upper portion of the outside of the paperboard outer container. The screw threads permit a cap to be screwed onto the container after product, e.g. food, is placed in the container. The screw threads are vacuum formed, preferably simultaneously with the blow forming of the plastic inner container.

What is claimed is: 
     
       1. The process for drawing and blow forming plastic into a paperboard outer container and vacuum forming plastic screw threads about the upper portion of said outer container comprising: (a) positioning in a female mold a paperboard outer container having a circular cross-section at its top and comprising at least one vertical wall so that an upper portion of said paperboard outer container extends outside said female mold;   (b) providing a male mandrel arranged and constructed so that it may engage the female mold;   (c) heating a layer of plastic;   (d) positioning said layer of heated plastic between said female mold and said male mandrel;   (e) drawing said plastic into said paperboard outer container positioned in said female mold whereby a first portion of said plastic abuts said male mandrel and is spaced from the interior of said paperboard outer carton and a second portion of said plastic extends in close proximity about the upper portion of the outside surface of said paperboard outer container;   (f) blow forming the plastic in said paperboard container into substantial abutment with said at least one vertical wall by directing gas from said male mandrel into the interior of said female mold;   (g) vacuum forming plastic screw threads about the upper portion of said outer container by applying a vacuum to said second portion of said plastic.   
     
     
       2. The process of claim 1 wherein steps (f) and (g) commence substantially simultaneously with the completion of step (e). 
     
     
       3. The process of claim 1 further comprising bonding a third portion of said plastic sheet onto the upper edge of paperboard outer container. 
     
     
       4. The process of claim 1 further comprising unscrewing said container from said male mandrel. 
     
     
       5. The process of claim 1 wherein the vacuum applied to said second portion of said plastic is about 1 to 30 inches. of mercury measured at the vacuum intake to the male mandrel.